Stephen Hawking passed away yesterday in his home at age 76. Hawking popularised the deepest questions of the universe and became a pop culture icon thanks to his writing and work. His personality and ideas had a profound impact on scientists and science fans alike.
Stephen Hawking in 2014, at the premiere for the movie The Theory of Everything. Photo: AP
Hawking will be remembered by many for his theory of Hawking radiation, a profound concept that linked the largest-scale physics of black holes with the tiniest quirks of quantum mechanics. His books influenced the way science communication happens today. I never read much fiction as a teenager, but consumed popular physics books voraciously. I consider Hawking part of the reason I write about physics today.
The director of the CERN research centre in Switzerland, Fabiola Gianotti, perhaps described Hawking best in a statement yesterday: "Each time Stephen Hawking visited CERN, we were impressed by his great enthusiasm, vitality and passion for knowledge. He was a brilliant example on how to face disease with courage. He was a warrior."
I reached out to some of the physicists I know and asked for their thoughts on Hawking. Here are their replies, and you can always read Hawking's own words yourself.
Avi Loeb, Chair, Harvard Astronomy Department and Author
Stephen embodied the superiority of mind over matter. He demonstrated that the human spirit can overcome all physical limitations and that the human mind can comprehend the deep secrets of nature. With his optimistic mindset, he discovered that even a black hole can shine brightly.
Barak Kol, Head of Hebrew University's Racah Institute of Physics
It is common knowledge that Prof Stephen Hawking was one of the greatest scientists of our time, as well as an inspiring instance of human spirit and humour in the face of illness and difficulty. It is perhaps less known that his single most scientific achievement, namely the theoretical discovery of Hawking radiation from black holes was intimately related to the ideas of the late Prof Jacob Bekenstein from the Hebrew University of Jerusalem. In 1972 Bekenstein, then a PhD student at Princeton University, suggested that black holes might have properties of heat (more precisely entropy, known today as Bekenstein-Hawking black hole entropy). This idea was met with disbelief as scientists, including Hawking, thought that black holes absorb everything, yet nothing can escape them, and therefore their temperature would have to be the absolute zero.
Yet in 1974 it was Hawking who discovered theoretically that once the effects of quantum physics are taken into account a weak radiation must escape that black hole. This radiation is known as Hawking radiation and it is accompanied by a temperature of the black hole. In this way it was Hawking who established and confirmed Bekenstein's earlier ideas and together they form the basis for Black Hole Thermodynamics, which is one of the pillars of contemporary theoretical physics. As this story illustrates, sometimes debate and even controversy, work towards a better and more united scientific understanding.
Chanda Prescod-Weinstein, Physicist, University of Washington
Stephen Hawking is the reason I became a physicist. And I am grateful that he set an example that one could be excellent at calculating and still care about social justice issues. He was on the right side of history about many things including Palestine and the need for a strong National Health Service, without which he could not have had the career that he had. Hawking set an important example of what a life in physics could be: Curious and in service of caring, not killing.
Stephen Hawking represented what is possible when there is a single payer health system and free college education.
Frank Wilczek, MIT Physicist and Nobel Laureate
Stephen Hawking was a colleague, a friend and an inspiration. My fondest memories of him come from the 1982 Nuffield Workshop at Cambridge, a milestone event in the modern high energy physics and cosmology, where I got to know him well. In the interstices of watching others develop the theory of cosmological fluctuations through inflation, and myself getting axion cosmology going, I had the joy of coming to understand Stephen's speech in real time, probing his deep knowledge and opinions, and sharing family experiences and jokes. It seemed amazing then, and it seems even more amazing in retrospect.
Grant Tremblay, Harvard Astrophysicist
His was an epochal mind that sought and found the symmetries of Nature.
Katie Mack, Assistant Professor of Physics at North Carolina State University and Science Communicator
It would be hard to overstate the influence Hawking has had on me. I first discovered his work through A Brief History of Time and his media appearances when I was about 10 years old. I was fascinated by the concepts: Black holes, spacetime, the Big Bang. I wanted to know everything, and I wanted most of all to be involved in that work. When I found out that someone with Hawking's job was called a cosmologist, I knew that was what I wanted to be. In my college admissions essays I said that in the future, I want Stephen Hawking's job. I was fortunate enough to meet Hawking a few times, first when I was a star-struck 14-year-old who stopped him after a talk to tell him I was a big fan of his work (he said, "Thank you very much") and later when I was a visiting graduate student and eventually a postdoc at Cambridge University. He even came to one of my talks at Cambridge.
A really massive fraction of the cosmologists of my generation were influenced and inspired by Hawking. But working in the area I do, I also frequently encounter his ideas in my research, and the insights and creativity he has contributed to theoretical cosmology have really been revolutionary. His work on black hole evaporation has been foundational to probing the murky reaches of the intersection between gravity and quantum mechanics. And he has continued to contribute to this field - even as recently as a year or two ago, he published cutting-edge work on some of the most important remaining questions about black holes, gravity, and quantum physics. He was absolutely one of the most respected and influential physicists within theoretical cosmology, completely separately from his public profile. It's very rare for a physicist - or any scientist - to have such an impact both professionally and publicly. His legacy will be immense and enduring.
Lionel London, Research Associate in the School of Physics and Astronomy at Cardiff University
In the balmy summer months of 1998, I was an intellectually smouldering adolescent, and Hawking's A Brief History of Time fanned the flames of my interests. He remains an incredibly inspiring and luminary figure. His achievements transcend complex social boundaries, and help point the way for all scientists to brighten and refine the shadowy corners of human understanding.
Priya Natarajan, Yale Astrophysics Professor and Science Communicator
I did not work with him formally, but I interacted with him during my PhD and he was very kind to me. He included me and my work in his BBC documentary Stephen Hawking's Universe when I was still a graduate student, as I had nice a science result on how to map dark matter using lensing that he was very excited about. He was always interested in my work both on dark matter and black holes, and whenever I ran across him in the past 10 years at conferences and science festivals he would ask me for science updates.
In my personal opinion, Stephen Hawking's legacies are multifarious - scientifically he helped us understand the true nature of black holes, the most enigmatic objects in the universe; he showed us how important its to engage with the public and he also showed us how to do it effectively, and last but not least he showed us what resilience looks like in the face of adversity by how bravely and gracefully he coped with his illness.
Sabine Hossenfelder, Research Fellow at the Frankfurt Institute for Advanced Studies and Author
Stephen Hawking dedicated his life to understanding space, time and the beginning of our universe. He went straight for the big questions without hesitation. But it's not only that his research contributions advanced the field. Hawking was also a skilled science communicator. He demonstrated that it's not only a few crazy physicists who care about the deep mysteries of the universe, but that this research has cultural relevance far beyond the confines of academia.
Thomas Hornigold, Physics Podcaster
When I was choosing what to study, it was between history (that I was super interested in) and physics (which I also loved, but wasn't sure I was good enough at to study it at a higher level). Naturally the decision was not easy. I remember reading my parents' copy of A Brief History of Time while I was writing up my motivation letter for colleges - and when I realised I could understand most of it, the decision was made for me.